The overall aim of this present study is to evaluate Growth Differentiation Factor-15 (GDF-15) and inflammatory cytokines as a possible novel and readily treatable target for the successful therapy of Anorexia Nervosa (AN). Therefore, GDF-15, neuronal and glial damage markers such as Neurofilament light chain (Nfl) and Glial fibrillary acidic protein (GFAP) and cytokines (such as Tumor necrosis factor alpha (TNF-α), Interleukin-6 (IL-6), and Interleukin 1β (IL-1β) levels will be assessed in the serum as well as in the cerebrospinal fluid of patients with diagnosed restrictive AN with and without exercising behavior compared to sex- and age-matched healthy controls to consolidate previous findings and to identify the main site of production of GDF-15 and cytokines in AN.